docs: def export(self, version, export_dir):
          """
          Create prov entities and activities.
          """
          atts = (
              (PROV['label'], self.label),
              (PROV['type'], NIDM_SEARCH_SPACE_MASK_MAP),
              (NIDM_RANDOM_FIELD_STATIONARITY, self.rf_stationarity),
              (NIDM_IN_COORDINATE_SPACE, self.coord_space.id),
              (NIDM_SEARCH_VOLUME_IN_VOXELS, self.search_volume_in_voxels),
              (NIDM_SEARCH_VOLUME_IN_UNITS, self.search_volume_in_units),
              (NIDM_SEARCH_VOLUME_IN_RESELS, self.search_volume_in_resels),
              (NIDM_RESEL_SIZE_IN_VOXELS, self.resel_size_in_voxels))
  
          # Noise FWHM was introduced in NIDM-Results 1.1.0
          if self.noise_fwhm_in_voxels is not None:
              if (version['major'] > 1) or \
                 (version['major'] >= 1 and
                      (version['minor'] > 0 or version['revision'] > 0)):
                  atts = atts + (
                      (NIDM_NOISE_FWHM_IN_VOXELS, self.noise_fwhm_in_voxels),
                      (NIDM_NOISE_FWHM_IN_UNITS, self.noise_fwhm_in_units))
  
          if self.expected_num_voxels is not None:
              atts = atts + ((NIDM_EXPECTED_NUMBER_OF_VOXELS_PER_CLUSTER,
                              self.expected_num_voxels),)
  
          if self.expected_num_clusters is not None:
              atts = atts + ((NIDM_EXPECTED_NUMBER_OF_CLUSTERS,
                              self.expected_num_clusters),)
  
          if self.height_critical_fwe05 is not None:
              atts = atts + ((NIDM_HEIGHT_CRITICAL_THRESHOLD_FWE_05,
                              self.height_critical_fwe05),)
  
          if self.height_critical_fdr05 is not None:
              atts = atts + ((NIDM_HEIGHT_CRITICAL_THRESHOLD_FDR_05,
                              self.height_critical_fdr05),)
  
          if self.extent_critical_fwe05 is not None:
              atts = atts + ((
                  SPM_SMALLEST_SIGNIFICANT_CLUSTER_SIZE_IN_VOXELS_FWE05,
                  self.extent_critical_fwe05),)
  
          if self.extent_critical_fdr05 is not None:
              atts = atts + ((
                  SPM_SMALLEST_SIGNIFICANT_CLUSTER_SIZE_IN_VOXELS_FDR05,
                  self.extent_critical_fdr05),)
  
          if self.search_vol_geom is not None:
              atts = atts + ((SPM_SEARCH_VOLUME_RESELS_GEOMETRY,
                              self.search_vol_geom),)
  
          if self.noise_roughness:
              atts = atts + ((NIDM_NOISE_ROUGHNESS_IN_VOXELS,
                              self.noise_roughness),)
  
          # Create "Search Space Mask map" entity
          self.add_attributes(atts)